Cryptocurrencies: He Steals $500,000 in USDC and Gets Ripped Off by an MEV Bot on Base

Caught is he who thought he would catch, wrote La Fontaine in The Rat and the Oyster. An anonymous hacker has just bitterly experienced this on Base, the layer 2 network of Ethereum operated by Coinbase. On August 6, 2026, he emptied the wallet of a victim through phishing, a technique that involves impersonating a trusted site to steal credentials. The announced loot: $501,650 in USDC vanished in seconds. A nice score. Except that while trying to convert this treasure into ETH on Uniswap, he overlooked a basic rule of on-chain trading. As a result, he lost three-quarters of the amount. Key points of this article: * A hacker stole $501,650 in USDC on Base, but his act turned into a fiasco when he lost three-quarters of the sum trying to convert the stolen funds. * An MEV bot exploited a poorly protected transaction on Uniswap V4, pocketing $370,000 through a sandwich attack, while the victim did not recover their funds. The story begins like dozens of others. According to Peckshield, the hacker siphoned approximately $501,650 in USDC from a victim's address on Base at 2:29 UTC on August 6, 2026. The funds landed on an address controlled by the attacker in mere moments. Up to that point, nothing unusual. The quick conversion of a stolen stablecoin into a harder-to-freeze asset is a classic move. The USDC, issued by Circle, can be frozen upon simple judicial request, unlike native ETH. The thief knew this. However, he was unaware of what awaited him on Uniswap. MEV: When the Hunter Becomes the Prey on Uniswap V4 Here lies the crux of the problem. To convert his USDC into wETH (the wrapped version of ether, compatible with ERC-20 token standards), the attacker went through a swap on Uniswap V4 without activating any protection against slippage, a mechanism that limits the acceptable deviation between the displayed price and the actual executed price of a transaction. Without this safeguard, the order remained exposed in plain sight in the mempool, the public waiting room where transactions linger before being recorded in a block. An MEV bot, one of those robots that track the maximum extractable value (the total profits a third party can derive by reordering pending transactions), spotted the prey. According to Value The Markets, on August 7, 2026, the bot placed a transaction just before the thief's to drive up the price, allowed the swap to execute at a degraded rate, and then sold right after. The classic sandwich technique, the attack that traps a transaction in a vise. For about 3.5 ETH in gas fees spent, the bot pocketed nearly $370,000. On Base, even thieves pay the slippage bill Rather than staying silent, the victim chose direct confrontation. Through on-chain messages, visible to anyone monitoring the concerned addresses, she publicly called out the hacker and the MEV bot operator, claiming to have identified the author of the theft. She even offered a 10% bounty on the amount in exchange for restitution. As of August 7, 2026, no funds had been returned, and no arrests had been announced. The thief thus retains about $129,000, the MEV bot has pocketed $370,000, and the victim has lost her entire initial stake. PeckShield, which reported the attack just hours after the events, specifies that neither the identity of the bot operator nor the phishing vector used against the victim has been made public. The anecdote is quite amusing. Base, whose stablecoin transfer volumes are among the highest of all Ethereum networks, logically attracts more and more MEV bots in search of poorly protected swaps, whether they belong to a distracted trader or a hasty robber. The chain executes what is written in the mempool, without distinction between a victim and her tormentor. Activating slippage protection or using a DEX aggregator capable of routing orders out of the bots' reach takes a few seconds for any user on Base. A simple precaution. This hacker, however, paid for this negligence with $370,000.

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